Discoverability of data transfer functionality

Mesh/case data transfer functionality (https://fluent.docs.pyansys.com/version/stable/user_guide/transfer_data.html) is obscure:

- The function is only accessible via an obscure module path, `ansys.fluent.core.utils.data_transfer import transfer_case`,
- There is no method on the session classes. This makes the functionality even less discoverable and could be a problem for the adoption of `PureMeshing` in particular.

Start with the transfer_data.html documentation and the ansys.fluent.core.utils.data_transfer import path for transfer_case. Trace the available session classes and decide which public entry points should expose this functionality. Done means the transfer feature is discoverable through the relevant session API and its documentation reflects the new entry point.

Written by the indexing model from the issue text.